assume cs:code
code segment 
    mov ax, 0ffffh
    mov ds, ax
    mov ax, 0020h
    mov es,ax
    mov bx, 0
    mov cs, 12
s:  mov dl, [bx]
    mov es:[bx], dl
    inc bx
    loop s  

    mov ax, 4c00h
    int 21h
code ends
end
